Different pre-analytical techniques and the results of 50 g oral glucose challenge tests.

OBJECTIVE: We aimed to analyse the pre-analytical process and its effect of 50 g of oral glucose challenge test results for screening gestational diabetes mellitus. RESEARCH DESIGN AND METHODS: The 50 g oral glucose challenge test was performed to 30 pregnant women, and the blood was collected as two samples for three tubes containing; serum separating jell (SSJ), sodium fluoride-potassium oxalate (NaF - KOx) and sodium citrate-containing tube. The first samples of the three tubes were centrifuged within 30 minutes, and second samples were centrifuged after 60 minutes and were analysed. One sample in SSJ tube and was analysed in the same day according to hospitals routine practice. The results were compared. RESULTS: Among the 30 samples, the mean decrease in glucose levels was highest in the SSJ tube (0.38 mmol/L), followed by 0.16 mmol/L in Na citrate tube and 0.14 mmol/L in NaF-KOx tube. The hospital routine assessment with SSJ was 6.36 ± 1.90 mmol/L. The <30 and >60 minutes glucose results were 6.80 ± 1.88 mmol/L vs 6.42 ± 1.97 mmol/L for SSJ, 5.95 ± 1.60 mmol/L vs 5.78 ± 1.51 mmol/L for Na Citrate and 6.90 ± 1.86 mmol/L vs 6.75 ± 1.90 mmol/L for NaF-KOx mg/dL groups, respectively, and both the changes within time and the results between the tubes showed a statistically significant difference (P < .001). CONCLUSION: In cases with longer assessment time and with different blood sample tubes, the clinician should also keep in mind that, especially with results under but close to the cut-off levels, an underdiagnosed gestational diabetes might be present.

Maternal serum glycosylated hemoglobin and fasting plasma glucose predicts gestational diabetes at the first trimester in Turkish women with a low-risk pregnancy and its relationship with fetal birth weight; a retrospective cohort study.

OBJECTIVE: To examine the accuracy of maternal serum glycosylated hemoglobin (HbA1c) and fasting plasma glucose (FPG) levels in predicting gestational diabetes at the first trimester in Turkish women with a low-risk pregnancy and its relationship with fetal birth weight. METHODS: This cohort study was conducted retrospectively in a tertiary referral hospital from January 2010 to January 2017. HbA1c and FPG serum concentrations were measured in 670 pregnant women at the first-trimester screening. HbA1c and FPG concentrations of women who subsequently developed gestational diabetes mellitus (GDM) were compared to those who did not, and its relationship with fetal weight was investigated. RESULTS: First-trimester screening was performed on 608 pregnant women, of whom 69 (11.3%) women had developed GDM. Median HbA1c and FPG concentrations were significantly higher in women developing GDM (n = 69) in comparison to those with uncomplicated pregnancies (n = 539) (5.31 ± 0.58% versus 5.01 ± 0.45%, p < .001 and 89.74 ± 8.71% versus 84.09 ± 9.16%, p < .001, respectively). The cut-off value calculated with the highest Youden index was HbA1c levels above 5.6% with a sensitivity of 34.78%, specificity of 89.8%, with a diagnostic accuracy of 83.55%, and FPG levels above 86.85 mg/dl with a sensitivity of 69.57%, specificity of 61.78%, with a diagnostic accuracy of 62.66%. The calculated odds ratio (OR) for HbA1c > 5.6% and FPG > 86 mg/dl were 4.69 (95% CI: 2.66-8.29), and 3.7 (95% CI: 2.15-6.35), respectively. HbA1c and FPG combined had improved the predictive capability for GDM (OR: 7.26, 95% CI: 3.71-14.19). According to correlation analyses, a noteworthy positive correlation was found between HbA1c and, FPG, 50 g GCT, age, BMI, parity, and birth weight. However, there was no correlation between FPG and birth weight. CONCLUSION: Diagnostic accuracy of HbA1c for GDM prediction in Turkish women with a low-risk pregnancy is 83.55% with a very good negative predictive value of 91.49%. HbA1c and FPG combined enhanced the predictive capability for GDM. In addition, there is a positive relationship between HbA1c and 50 g GCT, and birth weight. However, to suggest HbA1c as a potential screening test for gestational diabetes mellitus, further research is warranted.